Devices And Processes For Deasphalting And/Or Reducing Metals In A Crude Oil With A Desalter Unit

ABSTRACT

This invention relates to devices and processes for removing asphaltenes and/or metals from crude oil to increase refinery processing of heavy materials. The desalters of this invention reduce and/or remove at least a portion of asphaltenes and/or metals form the crude oil. The separation occurs by mixing water with the crude oil to result in an aqueous phase having water and water soluble salts, an interface phase having asphaltenes and/or metals along with water, and a hydrocarbon phase having desalted, deasphalted and/or reduced metal crude oil.

BACKGROUND

1. Field of the Invention

This invention relates to devices and processes for removing asphaltenesand/or metals from crude oil to increase refinery processing of heavyhydrocarbon feedstocks.

2. Discussion of Related Art

The current trend in refining includes utilization of heavier crude oiland alternative hydrocarbon sources, such as bitumen and tar sands.These heavier materials include an increased amount of asphaltenes andan increased amount of metals and/or heavy metals, which makesprocessing difficult due to among other things, viscosity, fouling, andcatalyst deactivation issues.

In response to this need, the petroleum refining industry has developedefforts and resources to develop new ways to solve problems associatedwith asphaltene-containing streams and metal-containing streams.However, such efforts have only partially succeeded in providingpractical methods and devices to maintain refinery capacity.

Solvent deasphalting is a commercially practiced process to separate theasphaltenes out of the heavy oils from a bottom of atmospheric and/orvacuum distillation towers. Solvent deasphalting units require highcapital expenditures and have high operating costs to recycle thesolvent.

Stephenson et al., U.S. Pat. No. 6,120,678 discloses desalting adjunctchemistry and teaches asphaltene dispersing treatments to reduce the raginterface. Stephenson et al. does not teach or suggest collectingasphaltenes and/or metals in a rag layer for separation from the crudeoil in a desalter.

Wilson et al., U.S. Pat. No. 3,779,895 discloses high temperature steamtreatment of asphaltene-containing streams to form an emulsion that isthen solvent deasphalted. Wilson et al. does not teach or suggestcollecting asphaltenes and/or metals in a rag layer for separation fromthe crude oil in a desalter.

Jorgensen, U.S. Patent Application Publication 2005/0211602 disclosessuperheated steam treatment of high boiling temperature material todemetalize the feed. Jorgensen does not teach or suggest collectingasphaltenes and/or metals in a rag layer for separation from the crudeoil in a desalter.

Gunnerman, U.S. Patent Application Publication 2005/0205463 disclosesusing ultrasound of a sufficient intensity to convert heavy hydrocarbonsin an emulsion to lighter components. Gunnerman does not teach orsuggest collecting asphaltenes and/or metals in a rag layer forseparation from the crude oil in a desalter.

Van der Toorn et al., U.S. Pat. No. 3,730,880 discloses problems ofcoking and catalyst issues for hyrdroconversion units when processingmaterials having asphaltenes and metals. Barger, U.S. Pat. No. 4,384,948discloses similar problems with coking and catalyst poisoning influidized catalytic cracking units when processing materials withasphaltenes and metals.

Although the foregoing disclosures provide advances in the art, there isstill a need for a method of removing asphaltenes and/or metals fromcrude oil, such as improved processability, reduced fouling, reducedviscosity, improved coke product quality, and/or, reduced catalystdeactivation.

SUMMARY

These and other aspects of this invention are met at least in part by aprocess and an apparatus for using a desalter to remove and/or reduce atleast a portion of asphaltenes and/or metals from the crude oil, such asto improve processability, reduce fouling, reduce viscosity, improvecoke product quality, reduce catalyst deactivation, and/or the like.

According to one embodiment, this invention relates to a desalter unitfor removing water soluble salts and asphaltenes from a crude oilstream. The unit includes a separator for receiving a water-in-oilemulsion formed from crude oil and wash water. The separator includes afirst nozzle for withdrawing an aqueous phase having water and watersoluble salts, a second nozzle for withdrawing an interface phase havingasphaltenes and water, and a third nozzle for withdrawing a hydrocarbonphase having desalted and deasphalted crude oil.

According to a second embodiment, this invention relates to a process ofdesalting and deasphalting crude oil. The process includes mixing a washwater stream and a crude oil stream to form a water-in-oil emulsion. Thecrude oil stream includes water soluble salts and asphaltenes. Theprocess includes separating the water-in-oil emulsion in a desalter unitto form a first stream having water and water soluble salts, a secondstream having asphaltenes and water, and a third stream having desaltedand deasphalted crude oil.

According to a third embodiment, this invention relates to a method ofincreasing asphaltene-containing crude oil processing capacity in arefinery with a hydroconversion unit having an asphaltene-basedoperating constraint. The method includes removing at least a portion ofasphaltenes from an asphaltene-containing crude oil in a desalter unit,and increasing a volume of the asphaltene-containing crude oil to therefinery until an amount of asphaltenes in a feed to the hydroconversionunit reaches the asphaltene-based operating constraint.

According to a fourth embodiment, this invention relates to a method ofincreasing metal-containing crude oil processing capacity in a refinerywith a hydroconversion unit having a metal-based operating constraint.The method includes removing at least a portion of metals from ametal-containing crude oil in a desalter unit, and increasing a volumeof the metal-containing crude oil to the refinery until an amount ofmetals in a feed to the hydroconversion unit reaches the metal-basedoperating constraint. The metals can be any metal, such as those thatdeactivate a heavy oil hydroconversion catalyst.

BRIEF DESCRIPTION OF THE FIGURES

The above and other features and aspects of this invention are betterunderstood from the following detailed description taken in view of thedrawings wherein:

FIG. 1 schematically shows a conventional desalter;

FIG. 2 schematically shows a single stage desalter, according to oneembodiment;

FIG. 3 schematically shows a two stage desalter, according to oneembodiment;

FIG. 4 schematically shows a partial configuration of refinery units,according to one embodiment;

FIG. 5 shows sample data corresponding to Example 1;

FIG. 6 shows sample data corresponding to Example 2; and

FIG. 7 shows sample data corresponding to Example 3.

DETAILED DESCRIPTION

As used herein the term “asphaltene” refers broadly to molecularsubstances found in crude oil, bitumen, tar sands, coal, intermediaterefinery streams and/or the like. Asphaltenes generally refer topolyaromatic carbon materials and/or polynuclear aromatic materialsfurther including hydrogen, sulfur, nitrogen, and/or metals. Typically,asphaltenes are defined operationally as the n-heptane (C₇H₁₆)insoluble, toluene (C₆H₅CH₃) soluble component of a carbonaceousmaterial. Often, individual asphaltenes aggregate into larger and/ormore complex structures. Asphaltenes may appear as a suspended solid ina hydrocarbon, but are distinguishable from other suspended matter, suchas mineral sediment.

Asphaltenes may also include aggregates of high molecular weightcompounds in heavy crude oils. Asphaltenes may be difficult to convertin hydroconversion processes into useful products, such as due tocoking, fouling, poisoning and the like. Asphaltenes can deactivatehydroconversion catalysts and cause various other problems in theseprocesses, such as precipitation in lines as sediment and/or plugging. Aconcentration of asphaltenes in the hydrocarbon feeds to thehydroconversion unit dictates the throughput and/or capacity. A higheramount of asphaltenes in the feed reduces the unit throughput. Inaddition, asphaltenes also may contain a substantial amount and/orfraction of sulfur, nitrogen, and metals. Most of the metals content ofthe crude oil supplied to the refinery may concentrate and/or collect inthe feeds to the hydroconversion units.

As used herein the term “metal” refers broadly an element that readilyloses electrons to form positive ions (cations) and may form metallicbonds between other metal atoms and/or may form ionic bonds withnon-metals. Metals may be described as a lattice of positive ionssurrounded by a cloud of delocalized electrons. On the periodic table, adiagonal line drawn from boron (B) to polonium (Po) may separate themetals from the nonmetals, such as elements to the lower left are metalsand elements to the upper right are nonmetals. An alternative definitionof metals may include overlapping conduction bands and valence bands intheir electronic structure. Some metals may include, but are not limitedto, barium (Ba), calcium (Ca), cerium (Ce), cobalt (Co), chromium (Cr),copper (Cu), iron (Fe), potassium (K), lithium (Li), magnesium (Mg),manganese (Mn), molybdenum (Mo), sodium (Na), nickel (Ni), lead (Pb),antimony (Sb), strontium (Sr), titanium (Ti), vanadium (V), zinc (Zn),zirconium, (Zr), and/or the like.

As used herein the term “heavy metals” refers broadly to metalcontaminates in crude oil, such as transition metals, some metalloids,lanthanides, and actinides. Heavy metals may have limited solubility inwater, such as vanadium and/or nickel.

As used herein the term “hydroconversion” refers broadly to catalyticprocesses with the addition of hydrogen to crack and/or break largermolecules into smaller components. Hydroconversion processes are used toprocess heavy petroleum fractions into lighter significantly morevaluable products by cracking and hydrogenation in a single reactor.These processes may include several variations, such as fixed bedresidue conversion units, ebullated bed reactors, slurry bed reactors,and/or any other suitable configuration. Hydroconversion processes mayoperate at high pressures and relatively low liquid space velocities,necessitating large thick-walled vessels. Efficient refinery operationsseek to maximize the use of lower cost heavy feedstocks whilemaintaining reliability and operability of downstream units, such as thehydroconversion unit.

This invention includes a novel process to increase heavy oil processingcapacity of a refinery and/or a field upgrader, such as a retrofit withvery low capital cost. This invention includes a low capital cost and alow operating cost process to debottleneck and/or increase a throughputand/or a capacity of a high pressure heavy oil or residuehydroconversion unit, where capacity is limited by theasphaltene-content and/or metal-content of the oil feed. The inventionseeks to use and/or employ partial deasphalting and/or partialdemetallation of the heavy crude oil feed to the refinery in a noveldesalting unit.

According to one embodiment, the novel desalter of this inventionenables removal of asphaltenes from crude oils in the desalter byforcing and/or driving the asphaltenes to concentrate and/or collect asa rag layer and/or an interface phase at the oil-water interface. Thedesalter unit may allow and/or provide for continuous and/orintermittent withdrawal and/or removal of the rag layer. The asphaltenesremoved by the desalter may be used and/or disposed of in the refineryby various options including processing in a delayed coker, a pyrolysisunit, and/or a gasifier. The process of the present invention mayenable; (a) an increase in the refinery capacity with very low capitalinvestment, and/or (b) the refinery to process less expensive and/orcheaper heavy crude oils and/or combinations of higher margin crudeslates or schedules.

In a refinery, the crude oil from storage tanks may be processed firstin a crude oil desalter, where impurities in the crude oil, such aswater, sediment, and water soluble salts can be at least reduced and/ormostly eliminated from the crude oil by thoroughly washing it with washwater, such as makeup water and/or recycle water. Various chemicals,such as demulsifiers can be injected into the desalter to improve theseparation between the aqueous and oil phases in the desaltingoperation. Electrodes can be used to create an electric field to enhancewater droplets coalescing and oil-water separation. A desalter unit ofthis invention can be one of the least expensive process units tooperate in a refinery. Furthermore, the desalter unit of this inventioncan be one of the simplest process units to operate, with respect toreliability and safety.

With heavy, high asphaltenic crude oils, a rag layer can form at theoil-water interface in the desalter unit. The rag layer may includewater, heavy hydrocarbons, asphaltenes, metals, heavy metals, and/orother impurities. Typically, but not necessarily, the rag layer lies atand/or is located near the crude oil-water interface in the desalter.Without being bound by theory, hydrogen bonding between the asphaltenesand water at the oil-water interface may play an important role in themovement of the asphaltenes to the oil-water interface and into the raglayer.

Conventional desalter operation minimizes the formation of the raglayer. If the rag layer becomes too large, it can adversely affect thedesalter performance, such as by water carryover into the oil phase. Ifthe rag layer moves too close to the electrode, the operation of thedesalter can also be adversely effected, such as causing an increase inpower consumption. Control and/or management of a rag layer in adesalter unit can often be difficult even with an addition of chemicaladditives.

In one embodiment, specially designed desalters can be equipped withoutlets to periodically or continuously withdraw the rag layer to helpprevent the above mentioned problems.

The process of this invention may include intentionally forming,creating, maximizing, and/or generating a rag layer in a heavy crude oildesalter unit. Specially formulated additives may be injected into thedesalter unit to selectively cause the metallic impurities, asphaltenesand/or any other undesirable compounds in the crude oil to concentratein the rag layer of the desalter unit. The desalter unit may includeadvanced level controls, online analyzers and/or mechanical extractioncapabilities to control, manage and/or remove the rag layer. The raglayer can be removed and/or blowndown periodically and/or continuously,such as for at least partial removal of the asphaltenes and otherundesirable impurities from the crude oil in the desalter unit. The raglayer formation rate can be controlled to create more or less volume orflow rate of rag layer as desired, such as to treat the varying levelsof asphaltenes, metals and/or other contaminates in different crude oilmixtures.

The apparatus of this invention may include novel desalter designs,additive injections, and/or optimized operations. Other changes to thedesalter operations, and any other device and/or action to accomplishrag layer formation and/or removal are within the scope of thisinvention.

For example and as a retrofit installation with an existing a singlestage desalter, the asphaltene separation process described above mayoccur in a second desalter vessel upstream of or parallel to the firstdesalter to maintain throughput and efficiency, such as to remove waterand/or salt.

Additional advanced separation techniques and/or additives may beemployed and/or used on the rag layer stream to process it further, suchas to separate a hydrocarbon portion from a water portion. Sometimes therag layer stream may be referred to as a waste stream, but may containuseful and/or recoverable water, hydrocarbons, fuel components, and thelike.

A hydrocarbon stream recovered from the rag layer may be sent to adelayed coker, mixed into the fuel oil pool, pyrolyzed to recover oiland/or energy, gasified to produce synthesis gas for further processingor disposal, and/or the like. The process of the present invention canadvantageously utilize refinery equipment and processes to minimizecapital Investment costs.

According to one embodiment, the invention includes a combination ofpartial deasphalting and demetallation of the heavy crude oil and/orresidue in a novel desalter operation prior to and/or followed by thehydroconversion operation.

Some potential benefits of the present invention include improvedeconomic benefits of crude oil processing in a refinery and/or in afield upgrader. The field upgrader may be at any suitable location, suchas in and/or near an oil field, an oil collection and/or distributioncenter or terminal, in and/or near a refinery, and/or the like.

Regarding hydroconversion units, due to the very high pressures and lowspace velocities employed in residue hydroconversion units, capitalcosts of these units can be extremely high. Partial deasphalting and/ordemetallation of the feed, feedstock, and/or supply to a hydroconversionunit may debottleneck and/or increase a processing capacity of thehydroconversion reactor. Desirably, the improved desalter allows,facilitates, and/or achieves increased hydroconversion capacity withlittle and/or no expense and/or modifications to the hydroconversionunit. Since the value improvement from processing a low valuehydrocarbon stream in a hydroconversion unit is high, increasing thecapacity of the reactor at minimal expense yields a high rate of returnfor a refinery or a field upgrader.

An additional benefit may include improved operability and/orreliability of the hydroconversion unit. Partial deasphalting and/ordemetallation of the feed to the hydroconversion unit may (i) lower thehydrogen consumption per barrel of the feed processed in thehydroconversion unit resulting in lower operating costs per barrelprocessed, (ii) improve the quality of the product from thehydroconversion unit, (iii) improve the operation of the hydroconversionunit by minimizing and/or reducing sediment formation, and/or (iv) helpreduce catalyst replacement or addition rates thereby reducing catalystcosts significantly.

Other benefits may include retrofitting this invention in an existingrefinery and/or a field upgrader. Desirably, this invention may: (i)increase the overall refinery capacity, such as without changing thecrude slate; and/or (ii) the refinery crude slate and/or combination offeedstocks may include incrementally heavier crude oils for lower costs.These benefits may significantly increase margins and/or profits.

According to one embodiment, this invention relates to a novel processfor partial deasphalting and demetallation of a crude oil in a desalterprior to processing the partially deasphalted and demetalated heavy oilor residue in a hydroconversion process unit.

Referring to FIG. 1, conventional desalters remove water soluble saltsfrom crude oil by combining a crude oil line 110 with a wash water line112 in a mixing device 120 to form an emulsion line 114. The emulsionline 114 is connected with respect to a separator 122 where the emulsionseparates into a desalted oil line 116 and a spent water line 118.

Referring to FIG. 2 and according to one embodiment for a single stagedesalter of this invention, a crude oil line 210 may combine with a washwater line 212 in a mixing device 220 to form an emulsion line 214. Theemulsion line 214 can be connected with respect to the separator 222where the emulsion can separate into a deasphalted oil line 216, a spentwater line 218, and a rag layer line 224. The rag layer line 224 may beconnected to a coker 226, a gasifier 228, a pyrolysis unit 230, a fuelsystem 232, and/or any other suitable use for processing and/ordisposal. The spent water line 218 may be processed in a waste watertreatment unit, for example.

Referring to FIG. 3 and according to one embodiment for a two stagedesalter of this invention, a crude oil line 310 may combine with a washwater line 312 in a mixing device 320 to form an emulsion line 314. Theemulsion line 314 can be connected with respect to the separator 322where the emulsion can separate into a deasphalted oil line 316, a spentwater line 318, and a rag layer line 324. The deasphalted oil line 316may be connected with respect to a second mixing device 340 where asecond wash water line 342 combines to form a second emulsion line 344.The second emulsion line 344 can be connected with respect to the secondseparator 346 to form a second deasphalted oil line 348 and a secondspent water line 350. Optionally, a water reuse line 352 utilizes atleast a portion of the second spent water line 350 to supply the washwater line 312, such as in a generally countercurrent arrangement withrespect to crude oil flow and wash water flow. Other cascadearrangements of desalters in series and/or parallel combinations arepossible without departing from the spirit and scope of this invention.

Referring to FIG. 4 and according to one embodiment for units in arefinery, a crude oil line 410 connects with respect to a desalter 412to form a deasphalted oil line 414 for feed to a crude unit 416. Thebottom of the barrel, high temperature boiling fractions and/or theheavies form the residue line 418 from crude unit 416. The residue line418 may be supplied to the hydroconversion unit 420, such as having oneor more operating constraints. Desirably, the supply and/or type ofheavy oil to the crude oil line 410 may be increased until the operatingconstraint of the hydroconversion unit 420 limits additional feed. Otherarrangements of refinery units are possible without departing from thespirit and the scope of this invention.

As used herein the terms “having”, “comprising”, and “including” areopen and inclusive expressions. Alternately, the term “consisting” is aclosed and exclusive expression. Should any ambiguity exist inconstruing any term in the claims or the specification, the intent ofthe drafter is toward open and inclusive expressions.

According to one embodiment, this invention includes a desalter unit forremoving water soluble salts and asphaltenes from a crude oil stream.The unit may include a separator for receiving a water-in-oil emulsionhaving crude oil and wash water. The separator may include a firstnozzle for withdrawing an aqueous phase having water and water solublesalts, a second nozzle for withdrawing an interface phase havingasphaltenes and water, and a third nozzle for withdrawing a hydrocarbonphase having desalted and deasphalted crude oil.

As used herein the term “desalter” broadly refers to devices,apparatuses, vessels, and/or any other suitable process equipment forseparating at least two phases and/or layers, and more desirably, atleast three phases and/or layers. Desalters may be used with crude oilstreams and/or any suitable subsequent refinery process stream, such asvacuum tower residue.

Desalters may remove water soluble salts, such as those containingsodium, magnesium, calcium, chlorides, bromides, and/or any othersuitable substance retained in an aqueous phase upon contact with water.Desirably, the desalter also serves and/or functions to dewater and/ordehydrate the crude oil, such as removing at least a portion of thewater from the hydrocarbon phase.

The separator may include a square shape, a round shape, a cylindricalshape, and/or any other suitable shape. Desirably, the separatorincludes one or more baffles, such as to increase an average and/or amean residence time and/or dwell time within the vessel. In thealternative, the baffles assist in the separation.

The separator may also include one or more electrodes to apply anelectric field, such as to increase coalescing of water droplets fromthe hydrocarbon phase. Desirably, but not necessarily, the desalterutilizes and/or employs gravity and/or density differences in thecomponents to affect a separation. In the alternative, the separatorutilizes and/or employs inertia forces and/or centrifugal forces toaffect a separation.

As used herein the term “nozzle” broadly refers to outlets, taps,connections, flanges, and/or any other suitable device for removaland/or drawing off of at least one phase, layer and/or stream from theseparator. Desirably, the separator includes at least three nozzles.

As used herein the term “crude oil” broadly refers hydrocarbon-basedmaterial with minimal processing and/or refining. Crude oil includesmaterials from various parts of the Earth. Crude oil may include lightand sweet crude with a relatively low amount of asphaltenes and/ormetals. In the alternative, crude oil may include heavy and sour crudewith a relatively high amount of asphaltenes and/or metals.

As used herein the term “emulsion” broadly refers to a stable and/or anunstable dispersion and/or suspension of one material immiscible withanother. Some emulsions form with agitation and some emulsions breakwith agitation, for example.

As used herein the term “water-in-oil emulsion” broadly refers to anemulsion system with a larger volume of oil than water. The oil may forma continuous phase, such as with the water dispersed within.

According to one embodiment, the desalter unit further includes a crudeoil line, a wash water line in combination with the crude oil line, anda mixing device upstream of the separator and downstream of the crudeoil line and the wash water line.

As used herein the term “line” broadly refers to a connection betweentwo or more locations. Lines may include pipes, channels, trenches,conduits, ducts, tubing, any other suitable connection between one ormore locations or items, and/or a flow of materials between the one ormore locations or items.

As used herein the term “mixing device” broadly refers to any suitableapparatus and/or mechanism for combining at least a portion of more thanone stream. Suitable mixing devices may include tees, tanks, mixingvalves, static mixers, in-line powered mixers, and/or any other processequipment for bringing more than one substance into contact with anothersubstance. Mixing devices may utilize shear forces, high pressure,turbulence and/or any other suitable mechanism.

According to one embodiment, the separator includes an electrostaticgrid. The electrostatic grid may apply and/or create an electric fieldin at least a portion of the vessel. Desirably, the electrostatic gridassists and/or aids in coalescing the water droplets from thehydrocarbon phase and/or layer, such as collecting polar water moleculesin a region and/or section of the vessel based on lines of flux. Theelectrostatic grid may include any suitable configuration and/or design.

As used herein the term “coalescing” broadly refers to the combiningand/or uniting of one or more smaller droplets of water and/or anaqueous solution or phase to form a larger droplet, a phase, and/or alayer.

According to one embodiment, the second nozzle includes variable heightadjustment, such as to allow and/or provide for a changing positionand/or location of the interface phase and/or rag layer. The height ofthe rag layer may change, such as based on flow rates, types of crudeoil, other chemical additives, and/or the like. The variable heightadjustment may include a float mechanism operating on a densitydifference between one or more of the aqueous phase, the interface phaseand/or the hydrocarbon phase, for example. In the alternative, thevariable height adjustment includes a probe and/or a level sensor todetect the location and/or position of the rag layer. A suitablemechanical driver and/or mechanism may then raise and/or lower theoutlet to a corresponding suitable position.

In the alternative, any of the first nozzle, the second nozzle and/orthe third nozzle include variable height adjustment.

According to one embodiment, the unit includes at least one chemicalinjection port for adding at least one additive or chemical which mayact as emulsifiers, demulsifiers, flocculants, deflocculants,coagulants, anticoagulants, precipitants, dispersants, pH modifiers(acids, bases, buffering agents, or anti-buffering agents), and/or anysuitable substances. The injection port may be in any suitable location,such as upstream and/or before the separator. In the alternative, theinjection port may be upstream of the mixing device. More than onemixing port is possible. The use of slip streaming a portion of a mainflow to mix and/or combine with an additive may improve processability,such as using wash water to dissolve or disperse a solid.

Emulsifiers generally at least increase and/or form emulsions.Demulsifiers generally at least decrease and/or break emulsions.Flocculants generally at least increase aggregation of substances.Deflocculants generally at least decrease aggregation of substances.Coagulants at least generally increase viscosity and/or thickness ofsubstances. Anticoagulants at least generally decrease viscosity and/orthickness of substances. Precipitants at least generally causeseparation from a solution. Dispersants at least generally causescattering of a substance, such as into a solution. In the alternative,dispersants may form and/or cause colloids including particles. pHmodifiers at least generally change and/or affect the measure of theacidity or alkalinity of a solution, such as the activity of dissolvedhydrogen ions (H+).

According to one embodiment, the unit may include at least onemeasurement probe for determining a height and/or a thickness of theinterface phase and/or rag layer. Suitable probes may includecapacitance probes, inductance probes, conductivity proves, switches,sight glasses, ultrasonic probes, float probes, density profiler orprobes, level probes, x-ray probes, radiation probes, and/or any othersuitable sensor. In the alternative, the probe measures any othersuitable attribute and/or characteristic of any part of the system, suchas moisture, density, conductivity, and/or the like.

According to one embodiment, the invention includes a method ofincreasing the processing capacity of a residue hydroconversion unit ina refinery. The method includes removing at least a portion ofasphaltenes from an asphaltene-containing crude oil in a desalter unit,and feeding the residue hydroconversion unit with an atmospheric residueor a vacuum residue derived from a desalted and at least partiallydeasphalted crude oil from the desalter unit.

As used herein the term “residue” broadly refers to a portion of a feedto a distillation tower that does to form the overhead stream, such as abottoms cuts and/or a lower fraction. Increasing processing capacityincludes adding an additional volume of heavy feed and/or adding anadditional amount and/or concentration of asphaltenes and/or metals.

According to one embodiment, the invention includes a process ofdesalting and deasphalting crude oil. The process includes mixing a washwater stream and a crude oil stream to form a water-in-oil emulsion. Thecrude oil stream includes water soluble salts and asphaltenes. Theprocess also includes separating the water-in-oil emulsion in a desalterunit to form a first stream having water and water soluble salts, asecond stream having asphaltenes and water, and a third stream havingdesalted and deasphalted crude oil.

As used herein the term “mixing” broadly refers to a combining,intimately combining, contacting, and/or putting together two or moreitems, materials, and/or streams.

As used herein the term “stream” broadly refers to any suitable flowand/or passage of a material and/or a substance.

As used herein the term “water soluble salts” broadly refers tosubstances of two or more elements typically having at least one ionicbond that at least partially dissolve and/or form a solution with water.

As used herein the term “separating” broadly refers to a setting apartat least a portion of at least one first substance, material, and/orstream from at least a portion of at least one second substance,material, and/or stream. Additional separations are possible withoutdeparting from the spirit and the scope of this invention. Desirably,the separation generates at least three distinct flows.

As used herein the term “desalted” broadly refers to a crude oil and/orany other substance with at least a reduced and/or lesser amount ofwater soluble salts than prior to the desalter unit and/or processing.

As used herein the term “deasphalted” broadly refers to a crude oiland/or any other substance with at least a reduced and/or lesser amountof asphaltenes salts than prior to the desalter unit and/or processing.

As used herein the term “dewatered” broadly refers to a crude oil and/orany other substance with at least a reduced and/or lesser amount ofwater than prior to the desalter unit and/or processing.

As used herein the term “demetalated” broadly refers to a crude oiland/or any other substance with at least a reduced and/or lesser amountof metals than prior to the desalter unit and/or processing According toone embodiment, the process of deasphalting crude oil further includesforming from the water-in-oil emulsion in a separator an aqueous phasecorresponding to the first stream, an interface phase corresponding tothe second stream, and a hydrocarbon phase corresponding to the thirdstream. In the alternative, the first stream includes water and watersoluble salts, the second stream includes asphaltenes and/or metals, andthe third stream includes desalted, dewatered, demetalated and/ordeasphalted crude oil. Desirably, but not necessarily, the desalted anddeasphalted crude oil has not contacted a hydrocarbon-based extractionsolvent, such as in a solvent deasphalting unit.

The process may include adjusting a location and/or a height of a nozzlefor the separating of the second stream based on changes in a height ora level of the interface phase. The variable height adjustment may allowfor withdrawing the rag layer regardless of the operating rates,conditions during both stable and dynamic events.

The process may further include detecting and/or measuring a height or alevel of the interface phase. Measuring the height and/or thickness ofthe rag layer may allow and/or facilitate adjustment of the flow ratefor removal of the rag layer, such as too little flowrate may allowwater carry over to the hydrocarbon phase and too much flowrate maycause valuable hydrocarbon product to be downgraded with theasphaltenes.

The separating the second stream may occur on a continuous basis, anintermediate basis, a periodic basis, on demand, and/or any othersuitable frequency or interval.

Desirably, but not necessarily, the process includes applying anelectrostatic charge to the desalter unit for coalescing water droplets.The electrostatic charge may be applied by one or more grids in theseparator.

According to one embodiment, the process may include injecting,supplying, and/or adding into the desalter unit and/or any suitable lineleading to the desalter, one or more emulsifiers, demulsifiers,flocculants, deflocculants, coagulants, precipitants, pH modifiers,and/or any other suitable material or chemical. These materials may bein any suitable form, such as a solid, a powder, a liquid and/or a gas.

As discussed above, the desalting process may include demetallationand/or demetalizing of crude oil. The crude oil stream may includemetals, such as barium, strontium, cobalt, nickel, vanadium, iron,and/or the like. The second stream from the desalter may include metals.The third stream may include at least partially desalted, deasphaltedand demetalated crude oil. The crude oil stream may include water. Thefirst stream may include water at least partially from the crude oilstream. The third stream may include desalted, deasphalted and/ordewatered crude oil.

According to one embodiment, the process includes removing, eliminating,reducing, and/or separating at least a portion of the asphaltenes, othercontaminants, and/or foulants from at least a portion of the water inthe second stream.

According to one embodiment, the process includes utilizing at least aportion of the asphaltenes as a fuel, such as to a fired boiler. In thealternative, the asphaltenes may be used and/or consumed as a feedstockand/or supply to a coking unit, a gasification unit, a pyrolysis unit,and/or the like. Coking units may include delayed cokers, fluidized bedcokers, thermal cokers, and/or any other suitable processing unit.Gasification units may include any suitable unit that converts at leasta portion of carbonaceous material into hydrogen and/or carbon monoxide.Pyrolysis units may include any suitable unit that heats a carbonaceousmaterial at least partially without and/or in the absence of oxygen.

According to one embodiment, the process includes controlling a rate ofrag layer formation, and controlling the rate of rag layer withdrawal.Controlling broadly includes varying in a desired or expected pattern orrange, such as to optimize the reduction of asphaltenes or metals in agiven crude oil. For example, raw crude oils with higher asphaltenes ormetals concentrations may benefit from higher levels or volumes ofasphaltenes or metals in the rag layer. Desirably, the combination ofthe concentration of impurities and the flow rate of the withdrawal(quantity) removes the contaminants from the desalted crude oil.

If the rag layer withdrawal rate increases, but the rag layer formationrate stays the same then asphaltene and metals concentration may bereduced and crude oil reductions may be less than desired. In contrast,crude oils with lower asphaltene and metals concentrations may requirelower rag layer withdrawal rates to achieve the desired result. If therag layer formation rate remains constant, then the rag layer can growand possibly carryover causing problems as stated above. Desirably, themethod can control the rate of formation of the rag layer and alsocontrol the rate of withdrawal of rag layer to optimize the asphalteneand metal removal efficiency for a given crude oil feed.

According to one embodiment, the process may be performed at or near theproducing field or hydrocarbon source, such as near an oil well, anoffshore platform, a bitumen source, a tar sands supply, and/or thelike. Field processing may provide improved transportation (lessfouling, less sediment, less corrosion, reduced viscosity, and/or thelike) and/or provide significant additional economic value (moremarketable, useful to additional refineries, and/or the like). In thealternative, the process may be performed at or near the refinery, suchas within the crude unit battery limits.

The apparatus and methods of this invention may include any suitableoperating temperature, such as at least about 0 degrees Celsius, atleast about 20 degrees Celsius, at least about 100 degrees Celsius, atleast about 150 degrees Celsius, and/or the like. The associated heatsource and/or the heat transfer equipment are also within the scope ofthis invention. According to one embodiment, this invention includes afeed effluent exchanger to reduce or recover heat or thermal energy.

According to one embodiment, this invention includes a method ofincreasing asphaltene-containing crude oil processing capacity and/orthroughput in a refinery and/or oil processing complex with ahydroconversion unit having an asphaltene-based operating constraint.The asphaltene-based operating constraint may include fouling, plugging,catalyst deactivation, and/or any other suitable limitation and/orboundary, for example. The method may include removing at least aportion of asphaltenes from an asphaltene-containing crude oil in adesalter unit and increasing a volume of the asphaltene-containing crudeoil to the refinery until an amount of asphaltenes in a feed to thehydroconversion unit reaches the asphaltene-based operating constraint.

For example and in a refinery operating against the asphaltene limit inthe feedstock to the hydroconversion unit, the desalter unit of thisinvention may reduce the asphaltene content of the crude oil by about 50percent in some crude oils. An amount of asphaltene-containing crude oilcan be about doubled in the feed to the refinery to maximize heavy crudeoil consumption and to operate against the asphaltene-based operatingconstraint of the hydroconversion unit.

Desirably, but not necessarily, the removing forms a first streamincluding water and water soluble salts, a second stream includingasphaltenes and water, and a third stream including desalted anddeasphalted crude oil. The method may include utilizing and/or supplyingat least a portion of asphaltenes as a fuel or as a feedstock to acoking unit, a gasification unit or a pyrolysis unit, as describedabove.

According to one embodiment, the hydrocarbon conversion unit includes ametal-based operating constraint and/or limit. The asphaltene-containingcrude oil may include metals. The step of increasing a volume and/orflowrate of the asphaltene-containing crude oil includes until an amountof asphaltenes in a feed to the hydroconversion unit reaches theasphaltene-based operating constraint and/or an amount of metals in afeed to the hydroconversion unit reaches the metal-based operatingconstraint. The term “reaches” includes the actual limitation and/or avalue and/or an amount safely below the constraint, such as to allow fornon-steady state or transient conditions, for example.

According to one embodiment, the invention includes a method ofincreasing metal-containing crude oil processing capacity in a refinerywith a hydroconversion unit having a metal-based operating constraint.The method may include removing at least a portion of metals from ametal-containing crude oil in a desalter unit, and increasing a volumeof the metal-containing crude oil to the refinery until an amount ofmetals in a feed to the hydroconversion unit reaches the metal-basedoperating constraint.

The metals may include any material discussed above, and mayspecifically include vanadium and/or nickel.

Desirably, but not necessarily, the removing may form a first streamincluding water and water soluble salts, a second stream includingmetals and water, and a third stream including desalted and demetalatedcrude oil.

EXAMPLES Example 1

A relatively heavy crude oil being processed at a mid-west U.S. refinerywas sampled. Five additional samples were taken of the rag layer of thefirst stage of the two stage desalter unit. The six samples wereanalyzed for metals content as shown in FIG. 5 with TABLE 1. Theanalysis for 21 metals was completed using inductively coupled plasma(ICP) spectroscopy on the six samples. The results listed in TABLE 1 arein parts per million on a mass basis. The rag layer emulsion wasresolved in the laboratory into a hydrocarbon phase and a water phase.The results in TABLE 1 correspond to the hydrocarbon phase of theemulsion.

The average of the five samples of the rag layer was taken and comparedto the metal concentration of the crude oil, such as the concentrationof the metals in the rag layer ranges from about equal to the crude oilfor vanadium, about 1,000× for magnesium, about 2000× for iron, about2,400× for aluminum, and about 87,000× for barium. The average metalconcentration in the rag layer exceeded the crude oil by more than about4,500×. These surprising and unexpected results show significant metalconcentrations in the emulsion (rag) layer. The concentration of themetals in the emulsion removes the metals from the crude oil before thedistillation unit and/or downstream catalytic units. The demetalatedcrude reduces corrosion, reduces fouling, reduces catalyst deactivation,and allows additional throughput.

Example 2

A different crude oil than Example 1 was being processed at the samemid-west U.S. refinery. There were samples taken from the raw crude oil,along with the desalter emulsion (rag layer), and the desalted crude oilexiting the desalter, as shown in FIG. 6 with TABLE 2. The samples wereanalyzed using inductively coupled plasma spectroscopy, as in Example 1.TABLE 2 shows the rag layer contained more metals than the raw crudeoil. Vanadium was about 1.5× more concentrated in the rag layer than theraw crude oil, sodium was over about 1,100× more concentrated in the raglayer than the raw crude oil, and aluminum was over about 3,300× moreconcentrated in the rag layer than the raw crude oil. The average of the22 metals was about 700× more concentrated in the rag layer than the rawcrude oil.

The metals in the desalted crude oil also showed a decrease over theconcentration in the raw crude oil. The desalted crude oil containedonly about 44 percent of the aluminum of the raw crude oil, the desaltedcrude oil contained only about 82 percent of the calcium of the rawcrude oil, and the desalted crude oil contained only about 91 percent ofthe chromium of the raw crude oil. The average of the 22 metals wasabout 96 percent of the metals in the desalted crude oil as in the rawcrude oil. These metals represent compounds not removed by aconventional desalter since the metals were at least somewhat soluble inthe hydrocarbon phase of the rag layer and not dissolved in the waterphase. The flow of the rag layer during the sampling was not optimizedfor maximum removal of metals and/or asphaltenes.

Example 3

A different crude oil than Example 1 or Example 2 was being processed atthe same mid-west U.S. refinery. There were samples taken from the rawcrude oil, along with the first stage desalter emulsion (rag layer), andthe second stage desalter emulsion (rag layer), as shown in FIG. 7 withTABLE 3. The samples were analyzed using titration method. TABLE 3 showsthe rag layer contained more asphlatenes than the raw crude oil. Theasphaltene concentration was about 3× more concentrated in the rag layerthan the raw crude oil of the first stage desalter rag layer. Theasphaltene concentration was about 5× more concentrated in the rag layerthan the raw crude oil of the second stage desalter rag layer. Theaverage of the two samples is about 4× more concentrated in the raglayer than the raw crude oil.

Surprisingly and unexpectedly, these asphaltenes represent compounds notremoved by a conventional desalter and are dispersed in the hydrocarbonphase of the rag layer and not dissolved in the water phase. The flow ofthe rag layer during the sampling was not optimized for maximum removalof metals and/or asphaltenes.

While in the foregoing specification this invention has been describedin relation to certain preferred embodiments, and many details are setforth for purpose of illustration, it will be apparent to those skilledin the art that this invention is susceptible to additional embodimentsand that certain of the details described in this specification and inthe claims can be varied considerably without departing from the basicprinciples of this invention.

1. A desalter unit for removing water soluble salts and asphaltenes froma crude oil stream, the unit comprising: a separator for receiving awater-in-oil emulsion comprising crude oil and wash water, the separatorcomprising a first nozzle for withdrawing an aqueous phase comprisingwater and water soluble salts, a second nozzle for withdrawing aninterface phase comprising asphaltenes and water, and a third nozzle forwithdrawing a hydrocarbon phase comprising desalted and deasphaltedcrude oil.
 2. The unit of claim 1, further comprising a a crude oilline; a wash water line in combination with the crude oil line; and amixing device upstream of the separator and downstream of the crude oilline and the wash water line.
 3. The unit of claim 1, wherein theseparator comprises an electrostatic grid.
 4. The unit of claim 1,wherein the second nozzle comprises a variable height adjustment.
 5. Theunit of claim 1, further comprising at least one chemical injection portfor adding emulsifiers, demulsifiers, flocculants, deflocculants,coagulants, precipitants, ph modifiers, or combinations thereof.
 6. Theunit of claim 1, further comprising at least one probe for determining aheight or a thickness of the interface phase.
 7. A method of increasingthe processing capacity of a residue hydroconversion unit in a refinery,the method comprising: removing at least a portion of asphaltenes froman asphaltene-containing crude oil in a desalter unit of claim 1; andfeeding the residue hydroconversion unit with an atmospheric residue ora vacuum residue derived from a desalted and at least partiallydeasphalted crude oil from the desalter unit of claim
 1. 8. A process ofdesalting and deasphalting crude oil, the process comprising: mixing awash water stream and a crude oil stream to form a water-in-oilemulsion, wherein the crude oil stream comprises water soluble salts andasphaltenes; and separating the water-in-oil emulsion in a desalter unitto form a first stream comprising water and water soluble salts, asecond stream comprising asphaltenes and water, and a third streamcomprising desalted and deasphalted crude oil.
 9. The process of claim8, further comprising forming from the water-in-oil emulsion in aseparator an aqueous phase corresponding to the first stream, aninterface phase corresponding to the second stream, and a hydrocarbonphase corresponding to the third stream.
 10. The process of claim 9,further comprising adjusting a location of a nozzle for the separatingof the second stream based on changes in a height or a level of theinterface phase.
 11. The process of claim 9, further comprisingdetecting a height or a level of the interface phase.
 12. The process ofclaim 8, wherein the separating the second stream occurs on a continuousbasis.
 13. The process of claim 8, further comprising applying anelectrostatic charge to the desalter unit for coalescing water droplets.14. The process of claim 8, further comprising injecting into thedesalter unit emulsifiers, demulsifiers, flocculants, deflocculants,coagulants, precipitants, pH modifiers, or combinations thereof.
 15. Theprocess of claim 8, wherein: the crude oil stream further comprisesmetals; the second stream further comprises metals; and the third streamcomprises desalted, deasphalted and demetalated crude oil.
 16. Theprocess of claim 8, wherein: the crude oil stream further compriseswater; the first stream further comprises water from the crude oilstream; and the third stream comprises desalted, deasphalted anddewatered crude oil.
 17. The process of claim 8, wherein the desaltedand deasphalted crude oil has not contacted a hydrocarbon-basedextraction solvent.
 18. The process of claim 8, further comprisingremoving at least a portion of the asphaltenes from at least a portionof the water in the second stream.
 19. The process of claim 18, furthercomprising utilizing the at least a portion of asphaltenes as a fuel oras a feedstock to a coking unit, a gasification unit or a pyrolysisunit.
 20. The process of claim 8, further comprising: controlling a rateof rag layer formation; and controlling a rate of rag layer withdrawal.21. The process of claim 8, wherein the process is performed at or nearthe producing field.
 22. A method of increasing asphaltene-containingcrude oil processing capacity in a refinery with a hydroconversion unithaving an asphaltene-based operating constraint, the method comprising:removing at least a portion of asphaltenes from an asphaltene-containingcrude oil in a desalter unit; and increasing a volume of theasphaltene-containing crude oil to the refinery until an amount ofasphaltenes in a feed to the hydroconversion unit reaches theasphaltene-based operating constraint.
 23. The method of claim 22,wherein the removing forms: a first stream comprising water and watersoluble salts; a second stream comprising asphaltenes and water; and athird stream comprising desalted and deasphalted crude oil.
 24. Themethod of claim 22, further comprising utilizing the at least a portionof asphaltenes as a fuel or as a feedstock to a coking unit, agasification unit or a pyrolysis unit.
 25. The method of claim 22,wherein: the hydrocarbon conversion unit includes a metal-basedoperating constraint; the asphaltene-containing crude oil includesmetals; the step of increasing a volume of the asphaltene-containingcrude oil comprises until an amount of asphaltenes in a feed to thehydroconversion unit reaches the asphaltene-based operating constraintor an amount of metals in the feed to the hydroconversion unit reachesthe metal-based operating constraint.
 26. A method of increasingmetal-containing crude oil processing capacity in a refinery with ahydroconversion unit having a metal-based operating constraint, themethod comprising: removing at least a portion of metals from ametal-containing crude oil in a desalter unit; and increasing a volumeof the metal-containing crude oil to the refinery until an amount ofmetals in a feed to the hydroconversion unit reaches the metal-basedoperating constraint.
 27. The method of claim 26, wherein the metalscomprise vanadium and nickel.
 28. The method of claim 26, wherein theremoving forms: a first stream comprising water and water soluble salts;a second stream comprising metals and water; and a third streamcomprising desalted and demetalated crude oil.